Kyoung-tae Kim

New RGB primary for various multimedia systems

Color gamut is one of the most important performance indicators of multimedia systems because a wide color gamut enables the reproduction of more real surface colors. The color gamut of multimedia systems depends on the RGB (red-green-blue) primary. There are various RGB primaries, such as ITU-R BT.709, ITU-R BT.2020, sRGB, Adobe RGB, and DCI-P3. ITU-R BT.709 and sRGB have a very small color gamut, while ITU-R BT.2020 has an extremely wide one. Adobe RGB and DCI-P3 have RGB primaries with the characteristics of color printers and digital cinema projectors, respectively. Also, some of these RGB primaries are not compatible with each other. Thus, the contents of a system should be converted for use in other systems. This paper proposes an RGB primary for use in various multimedia systems. In the proposed method, sRGB, Adobe RGB, and DCI-P3 – the most frequently used RGB primaries – are unified. In this paper, the color gamut efficiency and human visual preference of the proposed RGB primary are checked. The proposed RGB primary is expected to be utilized as an international-standard RGB primary for multimedia systems.

Development of laser-induced breakdown spectroscopy (LIBS) with timed ablation to improve detection efficiency

ABSTRACT A laser-induced breakdown spectrometer (LIBS) was developed for determining the elemental composition of individual airborne particles. The system employs two lasers focused on a narrow beam of particles. A continuous wave laser placed upstream scatters light from particles, while a pulse laser downstream ablates the particles. The scattered light from the upstream laser is used to trigger the downstream pulse laser, resulting in more accurate hitting of the particles than a free-firing laser system without the triggering signal (i.e., constant pulse laser firing). Various laboratory-generated aerosols (NaCl, MgCl2, KCl, and CaCl2) were used to evaluate the newly developed LIBS system. Particles were tightly focused into a center line with a sheath air focusing system using an optimum aerosol-to-sheath air velocity ratio. The locations of both the scattering laser and pulse laser beams were precisely controlled by a motorized X-Y stage controller. Data showed that for the LIBS with the triggering system, the hitting efficiency (%) of particles (200–600 nm) significantly increased (e.g., 350 nm particles had more than 26 times higher hitting efficiency at 1,000 particles/cm3), and much lower limits of particle size (∼200 nm) and number concentration (<100 particles/cm3) were achieved compared to the free-firing laser condition. Additionally, the hitting rate (hits/min) significantly increased with the triggering system. Our results suggest that the LIBS with the triggering system can be useful for real-time detection of elements of particles existing at low number concentrations (e.g., atmospheric particles) and for the determination of the variation of elemental composition among particles.